Can't get cement boards level

I'm installing tile floors for the first time. My subfloor is level, but as I lay my hardibacker I can't get the seams to level. They are perfect until I start to screw down the boards, then they shift up and down at random. Most of them are barely off, but one is almost 1/4" off. I'm assuming that's a big problem.

Before I lay tile, how can I make the boards level again at the seams?

Can't get cement boards level

So far I've laid 5 boards and only one seam of one of them is significantly out of level. Could I use patch and leveler to make it less dramatic?

No. You are not painting or laying vinyl, you are installing ceramic tiles which do not bend much. The floor needs to be flat.

Either the floor was not flat to start, or you created the hump while installing the boards. I bet the board lifted as you were driving the screws which can easily happen with Hardie. Is the problem along an entire seam or just near a screw?

Jaz

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Tile 4 You LLC Troy, MI

DITRA Installs - KERDI Watertight-Mold-Free Showers. I have NEVER made a mistake, I thought I did ONCE, but, I was WRONG!A+ BBB rating - est. 1987 - over 50 yrs. exp.

Can't get cement boards level

Quote:

Originally Posted by JazMan

No. You are not painting or laying vinyl, you are installing ceramic tiles which do not bend much. The floor needs to be flat.

Either the floor was not flat to start, or you created the hump while installing the boards. I bet the board lifted as you were driving the screws which can easily happen with Hardie. Is the problem along an entire seam or just near a screw?

Jaz

Correct, the board lifted as I was screwing. The separation is roughly 1/2 of the 5-foot length of board.

Each board rose slightly as I was installing screws, but fell back to level as I tightened. This one seam refuses to go back down. I removed the screws and installed them again about an inch away from each original hole and that didn't solve the problem.

Can't get cement boards level

Quote:

Originally Posted by SCarolina

Correct, the board lifted as I was screwing. The separation is roughly 1/2 of the 5-foot length of board.

Each board rose slightly as I was installing screws, but fell back to level as I tightened. This one seam refuses to go back down. I removed the screws and installed them again about an inch away from each original hole and that didn't solve the problem.

Well OK. I guess you knew what was happening but missed this section. Go ahead and cut this part out and redo it.

Jaz

__________________
Tile 4 You LLC Troy, MI

DITRA Installs - KERDI Watertight-Mold-Free Showers. I have NEVER made a mistake, I thought I did ONCE, but, I was WRONG!A+ BBB rating - est. 1987 - over 50 yrs. exp.